DOE OSTI2020
K3AlTe3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Te2- atoms. There are a spread of K–Te bond distances ranging from 3.62–4.24 Å. In the second K1+ site, K1+ is bonded to five Te2- atoms to form distorted KTe5 trigonal bipyramids that share corners with four equivalent AlTe4 tetrahedra, corners with two equivalent KTe5 trigonal bipyramids, an edgeedge with one AlTe4 tetrahedra, and an edgeedge with one KTe5 trigonal bipyramid. There are a spread of K–Te bond distances ranging from 3.50–3.66 Å. In the third K1+ site, K1+ is bonded in a 4-coordinate geometry to six Te2- atoms. There are a spread of K–Te bond distances ranging from 3.50–4.01 Å. Al3+ is bonded to four Te2- atoms to form AlTe4 tetrahedra that share corners with four equivalent KTe5 trigonal bipyramids, an edgeedge with one AlTe4 tetrahedra, and an edgeedge with one KTe5 trigonal bipyramid. There are a spread of Al–Te bond distances ranging from 2.61–2.71 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 7-coordinate geometry to five K1+ and two equivalent Al3+ atoms. In the second Te2- site, Te2- is bonded in a 7-coordinate geometry to six K1+ and one Al3+ atom. In the third Te2- site, Te2- is bonded in a 1-coordinate geometry to seven K1+ and one Al3+ atom.